MASCON—A Mass Consistent Atmospheric Flux Model for Regions with Complex Terrain

Abstract

MASCON was developed to provide air pollution models for the San Francisco Bay Area with mass consistent meteorological input data. Measurements of inversion base heights above topography and mean winds within the mixed layer calculated from surface observations of wind speed and direction were used as input data for the model. Variational calculus techniques were used to adjust the observed horizontal fluxes so they satisfied the continuity equation. In cases where air within the elevated inversion was entrained into the mixed layer, we used a parameterization of the vertical velocity. This model can also accept solid boundaries in the interior of the grid simulating conditions in the Bay Area where the base of the inversion is below some of the topographic features. This results in the horizontal flow fields being forced around these obstacles.